What material is Q355?
In engineering construction and manufacturing, Q355 is a common low-alloy high-strength structural steel that is widely used in bridges, buildings, vehicle manufacturing and other fields. This article will introduce the material properties, chemical composition, mechanical properties and application scenarios of Q355 in detail, and help readers fully understand this material through structured data.
1. Material properties of Q355
Q355 is a low-alloy high-strength steel. The "Q" in its name represents yield strength, and "355" indicates that its yield strength is 355MPa. Compared with ordinary carbon structural steel, Q355 has higher strength and better welding performance, as well as good plasticity and toughness.
| Features | Description |
|---|---|
| Yield strength | ≥355MPa |
| tensile strength | 470-630MPa |
| Elongation | ≥21% |
| Impact toughness | ≥34J（-20℃） |
2. Chemical composition of Q355
The chemical composition of Q355 has an important impact on its performance. The following is the main chemical composition range of Q355B (common grades):
| element | Content (%) |
|---|---|
| Carbon (C) | ≤0.20 |
| Silicon (Si) | ≤0.55 |
| Manganese (Mn) | ≤1.60 |
| Phosphorus (P) | ≤0.035 |
| Sulfur(S) | ≤0.035 |
3. Mechanical properties of Q355
The mechanical properties of Q355 are the key to its wide application in engineering fields. The following are its typical mechanical property data:
| Performance indicators | numerical value |
|---|---|
| Yield strength (MPa) | ≥355 |
| Tensile strength (MPa) | 470-630 |
| Elongation (%) | ≥21 |
| Impact energy (J, -20℃) | ≥34 |
4. Application scenarios of Q355
Q355 is widely used in the following fields due to its excellent comprehensive performance:
1.construction project: Used for steel structure frames of high-rise buildings and large venues, such as stadiums, convention and exhibition centers, etc.
2.bridge engineering: Suitable for main beams and supporting structures of long-span bridges.
3.vehicle manufacturing: Used in chassis and load-bearing parts of heavy-duty trucks and construction machinery.
4.pressure vessel: Q355 material will also be used in the manufacture of some low-pressure vessels.
5. Comparison between Q355 and other steels
In order to understand the characteristics of Q355 more intuitively, the following is its comparison with Q235 and Q420:
| Steel number | Yield strength (MPa) | Tensile strength (MPa) | Main features |
|---|---|---|---|
| Q235 | 235 | 375-500 | Ordinary carbon structural steel, good weldability |
| Q355 | 355 | 470-630 | Low-alloy high-strength steel with excellent comprehensive properties |
| Q420 | 420 | 520-680 | High-strength steel for heavy-duty structures |
6. Heat treatment and processing of Q355
Q355 is usually delivered in a hot-rolled state, but it can also be normalized upon request. Please pay attention to the following matters when processing:
1.Welding performance: Q355 has good weldability, but it needs to use low hydrogen electrode and control the preheating temperature.
2.Cold working: Can be used for cold processing such as shearing and stamping, but annealing should be performed when the deformation is large.
3.cutting: Suitable for thermal cutting methods such as flame cutting and plasma cutting.
7. Market status and development of Q355
As China's infrastructure construction continues to advance, the demand for Q355 steel has maintained steady growth. In recent years, with the proposal of the "double carbon" goal, the steel industry is developing in a green and low-carbon direction. The production process of Q355 is also constantly optimized. In the future, more high-performance, low-energy-consumption improved products will appear.
It can be seen from the above analysis that Q355, as a low-alloy high-strength steel with excellent performance and affordable price, plays an irreplaceable role in the field of engineering construction. Understanding its characteristics and correct usage is of great significance to both engineering design and material procurement.
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